Polycyclic extensions of semigroups

Abstract

In the paper we introduce a notion of the Bruck-Reilly $\lambda$-polycyclic extension of a monoid $S$ with a homomorphism $\theta$ which is an analogue of the Bruck-Reilly extension of a monoid $S$. We describe idempotens of the semigroup $\left({\mathcal{P}}_{\lambda }(\theta ,S),\ast \right)$ and Green's relations on $\left({\mathcal{P}}_{\lambda }(\theta ,S),\ast \right)$. It is proved that $\left({\mathcal{P}}_{\lambda }(\theta ,S),\ast \right)$ is a $0$-simple semigroup for any semigroup $S$. We find necessary and sufficient conditions on a monoid $S$ and a homomorphism $\theta$ under which the semigroup $\left({\mathcal{P}}_{\lambda }(\theta ,S),\ast \right)$ is regular, inverse, $0$-bisimple, combinatorial, congruence free, or inverse 0-E-unitary. Also we study topologizations of the semigroup $\left({\mathcal{P}}_{\lambda }(\theta ,S),\ast \right)$.

22 pages, in Ukrainian